Micromachines (also called micromechanical devices or microelectromechanical devices) are small (micron scale) machines which promise to miniaturize instrumentation in the same way microelectronics have miniaturized electronic circuits. Micromachines include a variety of devices such as motors and gear trains analogous to conventional macroscale machinery. As used herein, the term micromachine or microfabricated refers to any three-dimensional object having one or more sub-millimeter dimensions.
Micromachines have been applied to fluid systems, such as chemical delivery systems. Valves are the most important element in any fluid system because they are the building blocks for almost any kind of fluid control. Valves are essential to direct the flow of fluid and are necessary for most types of pumps. The most common valve in the realm of microfabricated devices is the diaphragm valve. Diaphragm valves come in many forms, but consist primarily of an actuated or energized diaphragm that pushes against an aperture associated with a fluid path. In such a system, the fluid flow is modulated by moving the diaphragm closer to or away from the fluid path aperture. The diaphragm may be actuated by any of a variety of methods including piezoelectric, electrostatic, bimetallic, and phase change.
Although diaphragm valves are not difficult to fabricate as individual devices, they are difficult to fabricate monolithically with other kinds of fluidic components, such as pumps and mixers. Bubble valves solve the problem of system integration. However, bubble valves can only withstand relatively low pressure differentials. Further, bubble valves require a relatively large amount of power, making them unsuitable for many applications.
Another problem with diaphragm valves is that they typically require a continuous input of power to maintain either the open or closed state. Continuous power input to maintain a valve state is a serious liability for low power applications.
In view of the foregoing, it would be highly desirable to develop a new type of microfabricated valve. More particularly, it would be desirable to develop a relatively high pressure valve that consumes a relatively low amount of power. Such a valve should be able to be monolithically fabricated with other fluid components, such as pumps and mixers.